ORIGINAL ARTICLE Lung metastases from differentiated thyroid carcinoma: prognostic factors related to remission and disease-free survival Saurav Chopra, Aayushi Garg, Sanjana Ballal and Chandrasekhar S. Bal Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India Summary Objective Distant metastases, although rare, account for maxi- mum disease-related mortality in differentiated thyroid cancer (DTC). Lungs and bones are the most frequent sites of metasta- ses. We sought to identify the prognostic factors in adult DTC patients presenting with pulmonary metastases at initial diagnosis. Design Retrospective cohort study. Patients From the medical records of 4370 patients, 200 patients aged more than 21 years who were identified to have pulmonary metastases at the time of diagnosis were included in the analysis. Results The sites of metastases were lungs alone in 133 (67%) patients, and additional sites in remaining 67 (33%) patients were as follows: bones in 59, liver in 4, brain in 2 and both bone and liver in two patients. During the mean follow-up of 61 months (range, 12–312 months), 76 patients achieved remission, 121 (60Á5%) patients had biochemically and/or structurally persistent disease and three patients showed disease progression. Multivariate analysis revealed pres- ence of macro-nodular (chest X-ray positive) pulmonary metastases and concomitant skeletal metastases as independent factors decreasing the likelihood of remission. Of the 76 patients with remission, 16 (21%) developed subsequent recur- rence. Patient age >45 years and follicular histopathology were independently associated with greater hazards of developing recurrence. Conclusion This study suggests that the patients with macro- nodular lung metastases and/or concomitant skeletal metastases have reduced odds of achieving remission. Moreover, significant number of patients recur even after complete remission with RAI treatment, hence strict surveillance is recommended espe- cially in patients with age >45 years and/or with follicular histol- ogy of DTC. (Received 4 June 2014; returned for revision 19 June 2014; finally revised 2 July 2014; accepted 12 July 2014) Introduction Differentiated thyroid cancer (DTC), which accounts for 90% of all thyroid cancers, comprises of two histologic types: papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC). 1 Unlike other malignant tumours, DTC has favourable prognosis with 10-year survival rates as high as 93% in PTC and 85% in FTC. 2 Distant metastases, although rare, account for maximum disease-related mortality. 3 Lungs and bones are the most fre- quent sites of metastases, with liver and brain being the rare sites. 4 The percentage of DTC patients with lung metastases has been reported to vary from 3% to 6%. 5–7 The 10-year survival rates in DTC patients with lung metastases range between 60% to 85%. 6,7 Lung metastases can be divided as metastases present- ing at initial diagnosis and metastases developing during the treatment course. These divisions have been shown to behave differently in terms of prognostic factors and response to treat- ment. 6 Majority of the studies on DTC patients with pulmonary metastases have determined the prognostic factors affecting the overall and cause-specific survival; 5–7 however, the disease-free survival and related prognostic factors have been inadequately studied in this group of patients. This study aimed at identifying the prognostic factors affect- ing remission and disease-free survival in DTC patients >21 years of age, presenting with pulmonary metastases at initial diagnosis. Materials and methods Patients From the medical records of 4370 patients treated for differenti- ated thyroid carcinoma at All India Institute of Medical Sci- ences, New Delhi, from 1970–2012, 3889 (89%) patients were aged >21 years. Of these, 204 (5%) patients were identified to have pulmonary metastases at the time of diagnosis. Four Correspondence: Chandrasekhar S. Bal, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi 110029, India. Tel.: +91-11-26593530; E-mail: csbal@hotmail.com © 2014 John Wiley & Sons Ltd 1 Clinical Endocrinology (2014) doi: 10.1111/cen.12558